Initialize tensor with fp32 in Caffe2Backend.prepare() (#15832)
Summary:
Fix https://github.com/pytorch/pytorch/issues/14104
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15832
Reviewed By: bddppq
Differential Revision: D13598332
Pulled By: yinghai
fbshipit-source-id: 3302ac47928974f49353c5da8af440e5c1716c22
